package com.baosight.hadoop.ch05;

import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

import java.io.IOException;
import java.util.Iterator;
import java.util.StringTokenizer;

/**
 * Created with IntelliJ IDEA.
 * User: dell
 * Date: 12-8-5
 * Time: 下午8:17
 * To change this template use File | Settings | File Templates.
 */
public class StudentScore extends Configured implements Tool {
    /**
     * Map class
     */
    public static class Map extends Mapper<LongWritable, Text, Text, IntWritable> {
        /**
         * Map class
         *
         * @param key
         * @param value
         * @param context
         * @throws IOException
         * @throws InterruptedException
         */
        public void map(LongWritable key, Text value, Context context)
                throws IOException, InterruptedException {
            String line = value.toString();
            System.out.println(line);

            StringTokenizer tokenizer = new StringTokenizer(line, "\n");
            while(tokenizer.hasMoreElements()) {
                StringTokenizer tokenizerLine = new StringTokenizer(tokenizer.nextToken());
                String strName = tokenizerLine.nextToken();
                String strScore = tokenizerLine.nextToken();

                Text name = new Text(strName);
                int scoreInt = Integer.parseInt(strScore);
                context.write(name, new IntWritable(scoreInt));
            }
        }
    }

    public static class Reduce extends Reducer<Text, IntWritable, Text, IntWritable> {
        public void reduce(Text key, Iterable<IntWritable> values, Context context)
                throws IOException, InterruptedException {
            int sum = 0;
            int count = 0;
            Iterator<IntWritable> iterator = values.iterator();
            while(iterator.hasNext()) {
                sum += iterator.next().get();
                count++;
            }

            int average = (int) sum/count;
            context.write(key, new IntWritable(average));
        }
    }

    public int run(String[] args) throws Exception {
        Job job = new Job(getConf());
        job.setJarByClass(StudentScore.class);
        job.setJobName("StudentScore");

        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);

        job.setMapperClass(Map.class);
        job.setCombinerClass(Reduce.class);
        job.setReducerClass(Reduce.class);

        job.setInputFormatClass(TextInputFormat.class);
        job.setOutputFormatClass(TextOutputFormat.class);

        FileInputFormat.setInputPaths(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));

        boolean success = job.waitForCompletion(true);
        return success ? 0 : 1;
    }

    public static void main(String[] args) throws Exception {
        args = new String[2];

        args[0] = "input";
        args[1] = "output";

        int ret = ToolRunner.run(new StudentScore(), args);
        System.exit(ret);
    }
}
